Medicaid programs throughout the nation are moving rapidly to enroll beneficiaries into managed care, partly due to the belief that managed care can improve care and reduce costs by lowering hospital emergency department (ED) use. Yet research on Medicaid managed care does not explain why variations remain in ED use. Nor does it examine the appropriateness of Medicaid managed care enrollee ED use by distinguishing between urgent and non-urgent visits. Furthermore, in contrast to the large body of literature on characteristics of ED users, few studies attempt to identity factors explaining why some members of a general population will use an ED. These population-based studies do not explore ED use by Medicaid beneficiaries enrolled in HMOs or other managed care programs. They also focus primarily on economic, rather than sociological or psychological, factors.The proposed study will address these research gaps. Poverty, lack of insurance, and physician unwillingness to serve Medicaid patients are the major reasons that low income people seek routine, non- urgent care in emergency departments. Yet once these barriers are overcome, for example, by enrollment in an HMO, other economic barriers, such as time and travel costs, as well as attitudes such as discussion with the primary care physician or a social preference for the ED, may help explain non-urgent ED use. To explore these questions, this study will combine data from responses to a survey distributed by the Colorado Department of Health Care Policy and Finance (the state Medicaid agency) to a representative sample of Medicaid HMO enrollees in late 1994 with data on ED and other medical care use by members of the survey sample enrolled in a large Colorado HMO (serving both Medicaid and commercial members for over 20 years). In addition to satisfaction with the HMO and its providers, the state's questionnaire included items regarding attitudes, knowledge, and beliefs about medical care. With non-urgent ED visits as the dependent variable, the study will use logistic regression to examine factors associated with the likelihood of non-emergency ED visits of Medicaid HMO enrollees using non-emergency ambulatory care. Results of this study should expand policy makers' understanding of why low income people use EDs and help state Medicaid agencies and managed care plans design systems that meet enrollee needs in order to reduce inappropriate ED use and improve continuity and quality of care.